Re: [Qemu-devel] [PATCH v10 7/8] generic-loader: Add a generic loader

[Alistair Francis]

On Tue, Aug 9, 2016 at 11:17 AM, Peter Maydell <address@hidden> wrote:
> On 3 August 2016 at 21:06, Alistair Francis <address@hidden> wrote:
>> Add a generic loader to QEMU which can be used to load images or set
>> memory values.
>>
>> Signed-off-by: Alistair Francis <address@hidden>
>> ---
>> V10:
>>  - Split out the PC setting and data loading
>> V9:
>>  - Fix error messages
>>  - Updated some incorrect logic
>>  - Add address space loading support for all image types
>>  - Explain why the reset is manually registered
>> V8:
>>  - Code corrections
>>  - Rebase
>> V7:
>>  - Rebase
>> V6:
>>  - Add error checking
>> V5:
>>  - Rebase
>> V4:
>>  - Allow the loader to work with every architecture
>>  - Move the file to hw/core
>>  - Increase the maximum number of CPUs
>>  - Make the CPU operations conditional
>>  - Convert the cpu option to cpu-num
>>  - Require the user to specify endianess
>> V3:
>>  - Pass the ram_size to load_image_targphys()
>> V2:
>>  - Add maintainers entry
>>  - Perform bounds checking
>>  - Register and unregister the reset in the realise/unrealise
>> Changes since RFC:
>>  - Add BE support
>>
>>  MAINTAINERS                      |   6 ++
>>  hw/core/Makefile.objs            |   2 +
>>  hw/core/generic-loader.c         | 195 
>> +++++++++++++++++++++++++++++++++++++++
>>  include/hw/core/generic-loader.h |  46 +++++++++
>>  4 files changed, 249 insertions(+)
>>  create mode 100644 hw/core/generic-loader.c
>>  create mode 100644 include/hw/core/generic-loader.h
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index 9c88c44..cc34ae0 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -984,6 +984,12 @@ M: Dmitry Fleytman <address@hidden>
>>  S: Maintained
>>  F: hw/net/e1000e*
>>
>> +Generic Loader
>> +M: Alistair Francis <address@hidden>
>> +S: Maintained
>> +F: hw/core/generic-loader.c
>> +F: include/hw/core/generic-loader.h
>> +
>>  Subsystems
>>  ----------
>>  Audio
>> diff --git a/hw/core/Makefile.objs b/hw/core/Makefile.objs
>> index cfd4840..939c94e 100644
>> --- a/hw/core/Makefile.objs
>> +++ b/hw/core/Makefile.objs
>> @@ -17,3 +17,5 @@ common-obj-$(CONFIG_SOFTMMU) += loader.o
>>  common-obj-$(CONFIG_SOFTMMU) += qdev-properties-system.o
>>  common-obj-$(CONFIG_SOFTMMU) += register.o
>>  common-obj-$(CONFIG_PLATFORM_BUS) += platform-bus.o
>> +
>> +obj-$(CONFIG_SOFTMMU) += generic-loader.o
>> diff --git a/hw/core/generic-loader.c b/hw/core/generic-loader.c
>> new file mode 100644
>> index 0000000..4ee71cb
>> --- /dev/null
>> +++ b/hw/core/generic-loader.c
>> @@ -0,0 +1,195 @@
>> +/*
>> + * Generic Loader
>> + *
>> + * Copyright (C) 2014 Li Guang
>> + * Copyright (C) 2016 Xilinx Inc.
>> + * Written by Li Guang <address@hidden>
>> + *
>> + * This program is free software; you can redistribute it and/or modify it
>> + * under the terms of the GNU General Public License as published by the
>> + * Free Software Foundation; either version 2 of the License, or
>> + * (at your option) any later version.
>> + *
>> + * This program is distributed in the hope that it will be useful, but 
>> WITHOUT
>> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
>> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
>> + * for more details.
>> + */
>> +
>> +#include "qemu/osdep.h"
>> +#include "qom/cpu.h"
>> +#include "hw/sysbus.h"
>> +#include "sysemu/dma.h"
>> +#include "hw/loader.h"
>> +#include "qapi/error.h"
>> +#include "hw/core/generic-loader.h"
>> +
>> +#define CPU_NONE 0xFFFFFFFF
>> +
>> +static void generic_loader_reset(void *opaque)
>> +{
>> +    GenericLoaderState *s = GENERIC_LOADER(opaque);
>> +
>> +    if (s->set_pc && s->cpu) {
>
> This check on s->cpu means that -device loader,file=<...> won't set the
> PC to the entry point unless you specifically pass cpu-num=0.
> The easiest fix for this is just to remove it (see below).

Fixed!

>
>> +        CPUClass *cc = CPU_GET_CLASS(s->cpu);
>> +        cpu_reset(s->cpu);
>> +        if (cc) {
>> +            cc->set_pc(s->cpu, s->addr);
>> +        }
>> +    }
>> +
>> +    if (s->data_len) {
>> +        assert(s->data_len < sizeof(s->data));
>> +        dma_memory_write((s->cpu ? s->cpu : first_cpu)->as, s->addr, 
>> &s->data,
>> +                         s->data_len);
>> +    }
>> +}
>> +
>> +static void generic_loader_realize(DeviceState *dev, Error **errp)
>> +{
>> +    GenericLoaderState *s = GENERIC_LOADER(dev);
>> +    hwaddr entry;
>> +    int big_endian;
>> +    int size = 0;
>> +
>> +    s->set_pc = false;
>> +
>> +    /* Perform some error checking on the user's options */
>> +    if (s->data || s->data_len  || s->data_be) {
>> +        /* User is loading memory values */
>> +        if (s->file) {
>> +            error_setg(errp, "Specifying a file is not supported when 
>> loading "
>> +                       "memory values");
>> +            return;
>> +        } else if (s->force_raw) {
>> +            error_setg(errp, "Specifying force-raw is not supported when "
>> +                       "loading memory values");
>> +            return;
>> +        } else if (!s->data || !s->data_len) {
>> +            error_setg(errp, "Both data and data-len must be specified");
>> +            return;
>> +        } else if (s->data_len > 8) {
>> +            error_setg(errp, "data-len cannot be greater then 8 bytes");
>> +            return;
>> +        } else if (s->data_len > sizeof(s->data)) {
>> +            error_setg(errp, "data-len cannot be more then the data size");
>
> This can't ever happen, because sizeof(s->data) is always 8.

Ok, removed.

>
>> +            return;
>> +        }
>> +    } else if (s->file || s->force_raw)  {
>> +        /* User is loading an image */
>> +        if (s->data || s->data_len || s->data_be) {
>> +            error_setg(errp, "data can not be specified when loading an "
>> +                       "image");
>> +            return;
>> +        }
>> +        s->set_pc = true;
>> +    } else if (s->addr) {
>> +        /* User is setting the PC */
>> +        if (s->data || s->data_len || s->data_be) {
>> +            error_setg(errp, "data can not be specified when setting a "
>> +                       "program counter");
>> +            return;
>> +        }
>
> Failing to specify cpu_num in this case needs to be an error.

Fixed.

>
>> +        s->set_pc = true;
>> +    } else {
>> +        /* Did the user specify anything? */
>> +        error_setg(errp, "please include valid arguments");
>> +        return;
>> +    }
>
>
>> +
>> +    qemu_register_reset(generic_loader_reset, dev);
>> +
>> +    if (s->cpu_num != CPU_NONE) {
>> +        s->cpu = qemu_get_cpu(s->cpu_num);
>> +        if (!s->cpu) {
>> +            error_setg(errp, "Specified boot CPU#%d is nonexistent",
>> +                       s->cpu_num);
>> +            return;
>> +        }
>> +    }
>
> If you always set s->cpu to be first_cpu in the "cpu_num is CPU_NONE"
> case you can avoid all the ?: everywhere you use it, and you don't need
> to check for 's->cpu' being non-NULL in the function where you set the PC.

Fixed.

>
>> +
>> +#ifdef TARGET_WORDS_BIGENDIAN
>> +    big_endian = 1;
>> +#else
>> +    big_endian = 0;
>> +#endif
>> +
>> +    if (s->file) {
>> +        if (!s->force_raw) {
>> +            size = load_elf_as(s->file, NULL, NULL, &entry, NULL, NULL,
>> +                               big_endian, 0, 0, 0,
>> +                               (s->cpu ? s->cpu : first_cpu)->as);
>> +
>> +            if (size < 0) {
>> +                size = load_uimage_as(s->file, &entry, NULL, NULL, NULL, 
>> NULL,
>> +                                      (s->cpu ? s->cpu : first_cpu)->as);
>> +            }
>> +        }
>> +
>> +        if (size < 0 || s->force_raw) {
>> +            /* Default to the maximum size being the machine's ram size */
>> +            size = load_image_targphys_as(s->file, s->addr, ram_size,
>> +                                          (s->cpu ? s->cpu : 
>> first_cpu)->as);
>> +        } else {
>> +            s->addr = entry;
>> +        }
>> +
>> +        if (size < 0) {
>> +            error_setg(errp, "Cannot load specified image %s", s->file);
>> +            return;
>> +        }
>> +    }
>
> Otherwise:
>
> Reviewed-by: Peter Maydell <address@hidden>

Thanks!

Alistair

>
> thanks
> -- PMM
>